Ambulatory infusion devices are known, for example, in the therapy of Diabetes Mellitus by Continuous Subcutaneous Insulin Infusion (CSII), as well as in pain therapy or cancer therapy. Those ambulatory infusion pumps are manufactured, among others, by Disetronic Medical Systems AG, Switzerland, and are available, e.g., under the name ACCU-CHEK® Spirit for CSII therapy.
The above-referenced ambulatory infusion devices are typically a syringe driver type. A number of drawbacks of such syringe driver type devices are known in the art. In particular, these devices have limited precision because they meter very small drug amounts, typically in the nano-liter range, out of a drug cartridge having an overall drug volume in the milliliter range. Therefore, additional concepts and architectures have been proposed that use a dedicated dosing unit downstream from the drug reservoir. These concepts include a micro membrane pump or a micro piston pump that are coupled to a drug reservoir and designed for precise metering of small volumes. While several designs for such dosing units are known in the art, they are complex, expensive and difficult to manufacture at a large scale because they integrate a number of components, including metering components and valves, and are frequently made from materials that are costly and/or difficult to manufacture, such as silicon. Accordingly, improved dosing units and ambulatory infusion devices comprising dosing units are required.